1. Technical Filed
The present invention relates to a canister provided with a leak detection valve.
2. Related Art
One example of a conventional canister is shown in FIG. 6.
With reference to FIG. 6, a canister is provided with a canister case 50 and a filter case 52. The filter case 52 is disposed above the upper end portion of the canister case 50 through an air (atmospheric air) communication port 51 in a vertically illustrated state. The filter case 52 is equipped with a filter element 53 for capturing or trapping dust in the air at a time of introducing the air into the filter case 52 and a leak detection valve 55. This leak detection valve 55 is disposed closely to the air communication port 55 of the canister case 50 in an air-tight manner.
In this conventional structure, since the filter case is not welded to the canister case 50, the filter case 52 is dispose detachably to the canister case 50. Accordingly, when it is required to change the leak detection valve 55, it is required to once remove the leak detection valve 55 after the removal of the filter case 52 from the canister case 50, thus being inconvenient.
Furthermore, the leak detection valve 55 is provided with at least two O-rings 56,56 to air-tightly mount the same to the filter case 52 and one O-ring 57 to be connected to the canister case 50. These O-rings 56 and 57 serve as seal members for preventing air or like from leaking. In FIG. 6, arrows show flow direction of fuel steam or outside air, for example.
As mentioned above, in the canister of the conventional structure such as shown in FIG. 6, at a time of changing or removing the leak detection valve of the canister, it is required to remove the filter case from the canister before the removal of the leak detection valve, thus being inconvenient and troublesome.
In addition, in the conventional structure, since the filter case cannot be welded to the canister case, it cannot be integrally formed with the canister case and these two members are required to be independent two parts, increasing number of parts, with much manufacturing cost in comparison with the manufacture of the integral structure. Furthermore, a working for attaching the filter case to the canister case will be required, which may adversely influence the productivity thereof.